Sprayable material changer apparatus

ABSTRACT

Apparatus is disclosed for communicating a plurality of fluidized sources with a spray apparatus. A plurality of sources are communicated to individual ones of a plurality of ports extending through a stationary plate member. A rotary and longitudinally displaceable plate member is arranged in alignment with the stationary plate member and is provided with a single orifice which communicates with the spray apparatus. The rotary plate is further provided with means forming a sealing member which are arranged to cooperate with gasket means provided for each of the source orifices on the stationary plate member so as to sealingly close the nonselected orifices and to provide for contamination free communication between the selected source orifice and the single orifice on the rotary plate member.

United States Patent 11 1 [11] 3,924,810

Otterstetter Dec. 9, 1975 SPRAYABLE MATERIAL CHANGER PrimaryExaminerLloyd L. King APPARATUS Attorney, Agent, or FirmRobert A.Benziger; Keith [75] Inventor: Charles H. Otterstetter, Southgate,Zerschlmg Mich' 57 ABST (3 RA T [73] Assignee: Ford Motor Company,Dearborn, 1

Mich. Apparatus is disclosed for communicating a plurallty of fluidizedsources with a spray apparatus. A plurality Flledl 1974 of sources arecommunicated to individual ones of a [21] APPL No; 520,759 plurality ofports extending through a stationary plate member. A rotary andlongitudinally displaceable plate member is arranged in alignment withthe sta- [52] US. Cl. 239/305 tionary plate member and is provided witha single ori- [51] Int. Cl. A62C 31/00 fice which communicates with thespray apparatus, [58] Field of Search 239/112, 15, 596, 305 The rotaryplate is further provided with means form- 5 ing a sealing member whichare arranged to cooperate References Cited with gasket means providedfor each of the source ori- UNITED STATES PATENTS fices on thestationary plate member so as to sealingly 2,257,004 9/1941 Fleming239/305 Close the nonselected Ofifices and to Pwdde for 3,348,774lO/l967 Wiggins 239/305 Lamination free Communication between theSelected 3,674,207 7/1972 Carbonetti, Jr. et al 239/305 Source Orificeand the Single Orifice 0n the rotary plate 3,782,632 1/1974 Braun et al.239/305 member. 3,793,049 2/1974 Probst 239/15 5 Claims, 5 DrawingFigures US. Patfint Dec. 9, 1975 Sheet 1 of2 3,924,810

SPRAYABLE MATERIAL CHANGER APPARATUS BACKGROUND OF THE INVENTION 1.Field of the Invention The present invention relates to the field ofspray apparatus in general and more particularly to that portion of theabove-noted field which is concerned with the spraying of material suchas for coatings. The present invention is more particularly directed tothat portion of the above-noted field wherein a plurality of materialsmust be intermittently sprayed in a random sequence fashion and whereinit is highly desirable to avoid any cross contamination of the material.More particularly still, the present invention is directed to apparatusfor use in association with an electrostatic powder spray apparatus forproviding that powder spray apparatus with communication to a pluralityof dry powder sources in a manner which will allow rapid change ofpowder communication from a first selected powder to a second selectedpowder and which will avoid any cross contamination of the powder beingsprayed with residue from a previous spray operation.

2. Description of the Prior Art In the spraying of dry powder materialssuch as film forming coatings on, for example, automotive body panels,it is frequently necessary to have a single spray station spray adifferent powder coating on each of a succession of body panels. Asingle spray station may have one or more spray apparatus, typicallyreferred to as spray guns, arranged to spray the material in unison. Inorder to maintain the speed of the spray assembly operation at a smoothand economically rapid level, it is necessary that the spray apparatusbe capable of changing from one sprayable material to another sprayablematerial in approximately the same amount of time as that required forthe successive body panel to come into the range of the spray apparatus.It is therefore a general objective of the present invention to providea means for changing the material being supplied to a spray station inthe time period required for successive parts to enter the spraystation.

One way in which this objective may be obtained is to provide each spraymaterial with separate spray apparatus and to automatically changebetween successive spray apparatus for each successive body panel.However, this is an expensive and awkward solution to the problem inview of the fact that powder coating materials are normally sprayed withan electrostatic charge to facilitate uniform deposition of the uniformcoating and the provision of a plurality of spray apparatus wouldnecessitate the provision of a plurality of electrostatic chargingdevices. Such a solution would also be cumbersome in the sheer bulk ofequipment required to be maintained at any one spray station.Furthermore, a safety hazard would be introduced by the additionalmachinery required to switch between successive spray apparatus and bythe necessity of maintaining a large number of electrostatically chargedpieces of spray apparatus. It is therefore an object of the presentinvention to provide a changer for spray apparatus which mayintercommunicate a single spray apparatus with a plurality of sprayablematerial sources.

One mechanism which has been successfully used in the past to achievethe aforementioned objective has been to provide a plurality of powdermanifolds each having a spray channel and a powder channel. Themanifolds are interconnected to align the spray channel so as to providea common passage through the manifold. Each powder channel intersectsthe spray or common passage and communicate with a single materialsource. Such an apparatus is thereafter. controlled by sequentialvalving situated in the powder channel upstream from the junction ofthat channel with the spray passage. This valving may open individualpowder channels and will concomittently close all other powder channelsto prevent any cross contamination. However, such valving apparatus,situated as it must be within the powder channels slightly upstream fromthe junction of the respective powder channel with the spray channel,provides a small pocket area where residue spray material mayaccumulate. While it is normally the custom to provide for a flushingoperation of the spray channel and of the spray apparatus betweensuccessive applications of material by the spray apparatus, the pocketsof accumulated spray material are difficult to thoroughly flush andfrequently result in contamination of the material being sprayed by aresidue of material from a previous spray operation. It is therefore afurther and specific object of the present invention to provide amaterial changer apparatus for use in conjunction with a spray apparatuswhich may intercommunicate the spray apparatus with a plurality ofsprayable material sources and which will prevent any crosscontamination of the sprayable material. More specifically, it is anobject of the present invention to provide such apparatus which willavoid the formation of accumulation regions downstream from the controlvalving to thereby avoid the formation of residue of sprayable material.

Still another attempt to solve the above noted problem has been toprovide the spray apparatus with a plurality of material supplyconduits. The supply conduits are arranged to have each of their exhaustports aimed or focused to deliver streams of material to be sprayed tothe center of a vortex nozzle. This a single material may be suppliedfrom a selected supply conduit and may be sprayed by the apparatus. Thespray nozzle may be subsequently communicated to a different supply.This arrangement is size limited in that only a small number of conduitsmay be arranged to be focussed toward the center of the vortex and isfurther complicated by the fact that the vortex aiming is critical. Itis therefore a further and specific object of the present invention toprovide material changer apparatus for a spray apparatus which maycommunicate that spray apparatus with a large plurality of sprayablematerial sources or reservoirs. It is a still further and particularobject of the present invention to provide such an apparatus in whichplacement of the means for communicating the changer apparatus with thematerial reservoirs may be noncritical in use. It is a still furtherobject of the present invention to provide such apparatus which mayautomatically change the communication of the spray apparatus from afirst selected material reservoir to a second selected materialreservoir while providing an intermediate flushing action. Moreparticularly still, it is an object of the present invention to providea changer apparatus which may intercommunicate a plurality of fluidizeddry powder sources with an electrostatic spray apparatus which isinexpensive and reliable and which avoids cross contamination of sprayedpowders. Other and further objects of the present invention will beapparent from the description which follows and the claims which areappended.

SUMMARY OF THE PRESENT INVENTION The present invention provides avalving mechanism comprised'of a pair of relatively movable platemembers. One plate member is arranged to be stationary and the otherplate member is arranged for rotary and translatory movement. Thestationary plate member is provided with a plurality of passagesextending therethrough, one of which may be communicated to a source offlushing fluid and the remainder of which may be communicated to aplurality of reservoirs of sprayable material. The movable plate memberis provided with a single passage means which may be arranged tocommunicate with the spray apparatus on the one side and, throughsuitable translatory and rotary movement of the plate, with selectedones of the stationary plate passages. Each of the stationary platemember passages may be provided with means defining a gasket seat orridge surrounding the orifice thereof while the rotary plate member maybe provided with means defining sealing structure to cooperate with thegasket seat or ridge provided on the stationary plate member to providefor sealing of each of the stationary plate member passages when theplate members are closely proximate to each other.

In order to achieve the desired translatory movement of the movableplate member, a double acting piston and cylinder means is providedinterconnecting the stationary and movable plate members which may berendered operative to translate the movable plate member toward and awayfrom the stationary plate member. In order to accomplish the desiredrotational movement of the movable plate member, a stepping motor meansmay be provided to rotate the movable plate member clockwise andcounterclockwise about an axis so as to align the movable plate memberpassage means with selected ones of the stationary plate member passagemeans.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 illustrates a side sectionalview of the changer apparatus according to the present invention.

FIG. 2 illustrates an end view of the apparatus of FIG. 1.

FIG. 3 illustrates in a schematic diagram form the present invention asapplied to an electrostatic powder coating spray operation.

FIG. 4 illustrates a block diagram for one form of a control system forcontrolling the material changer apparatus according to the presentinvention and useful in a system according to FIG. 3.

FIG. 5 illustrates an alternate embodiment of the valve sealing for thechanger according to the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawing,FIG. 1 illustrates the material changer apparatus according to thepresent invention. For purposes of illustration, the present inventionwill be described hereinbelow with reference to the application ofvarious color fluidized powder film forming materials by electrostaticspray deposition methods to automotive vehicle body panels. It will beappreciated that the present invention is applicable to spray apparatusother electrostatic spray apparatus and with sprayable materials otherthan dry powder filmforming coating material.

Powder changer apparatus 10 is comprised of a stationary plate member 12and a movable plate member 14 which is supported for rotation about axis16. Plate member 12 has a powder supply side 18 and a sealing surfaceside 20. Plate member 12 is provided with a plurality of passages 22which extend therethrough from the powder supply side 18 to the sealingsurface side 20. Each of the passages 22 may be communicated, forexample, by means of hoses 24 with a source of fluidized powder and bymeans of hose 26 with a source of a flushing agent as will be describedhereinbelow.

Stationary plate member 12 is connected to the movable plate member 14by cylinder means 28 which is illustrated as being attached to thepowder supply side 18 of the stationary member 12. Cylinder means 28includes a double acting piston member 30 situated within the cylindercavity 32. Piston 30 is arranged for reciprocating movement withincylinder means 28 and is provided with stub shaft member 34 whichextends through the stationary member 12 and is fixedly attached tomovable plate member 14. It will be appreciated that stub shaft member34 should be provided with some form of pressure retaining sealingbetween it and stationary plate member 12. Piston member 30 is arrangedto be actuated in the first direction by fluid pressure provided tocylinder cavity 32 through fluid conduit 36 and is arranged to beactuated in a second or opposite direction by fluid pressure provided tocylinder cavity 32 through fluid conduit 38. Piston 30 is furtherprovided with a pair of seal members 40 which operate to seal each endof the piston 30. As illustrated, seal members 40 may be, for example,flexible O-rings or such other seal means as are convenient.

The application of fluid pressure through fluid conduit 36 and fluidpassage 42 to face 46 of piston 30 is operative to displace piston 30rightward relative to FIG. 1, and through its connection to the movableplate member 14 by stub shaft 34, to cause movable plate member 14 totranslate rightwards. The application of fluid pressure through fluidconduit 38 and fluid passage 44 to the right hand face 48 of piston 30,relative to FIG. 1, will be operative to cause piston 30 to translateleftward relative to the figure. Due to the interconnection of piston30, stub shaft 34 and movable plate member 14, leftward movement ofpiston 30 will cause the movable plate member 14 to also translateleftward.

Each of the material supply hoses 24 and the flushing material supplyhose 26 is arranged to extend through stationary plate member 12 fromthe supply side 18 to the sealing surface side 20. The hoses 24, 26 areterminated in an extending flange portion 50 which generally surroundsthe passages 22 of the stationary plate member 12. Each flange portion50 is provided with a gasket seat or ridge 52 which may be, for example,a ridge portion formed as a part of the flange portion 50. Ridge 52 mayalsso be a separately embedded member or annulus of suitable materialsuch as metal.

Movable plate member 14 is provided with means defining a single fluidpassage 54 which communicates on the one side with spray apparatussupply hose 56 and is arranged to communicate on the other side with asimilarly provided passage 58 which extends through cooperating sealelement 60. In a preferred embodiment, cooperating seal element 60 is anannular band of natural rubber material which extends around theperiphery of the inner side of movable plate member'14. Cooperating sealelement 60 is provided with a single passage 58 and is thereforeoperative, when movable plate member 14 is in the extreme leftwardposition relative to FIG. 1, to cooperate with the gasket seats orridges 52, and the flange portions 50, of each of the hoses 24, 26 toseal the hoses from the environment. In the case of the selected, hereillustrated as hose 26, which is in fluid communication with sprayapparatus supply hose 56, the sealing action of cooperating seal element60 and gasket seat or ridge 52 will be to provide for fluid tightcommunication from the selected one hose 24 and the spray apparatussupply hose 56.

A second stub shaft 62 is attached to piston 30 so as to extend awayfrom face 46 of piston 30. This stub shaft 62 extends through cylinder28 and may be connected, for example, by a sliding spline connection, toa stepping motor 64. When energized, stepping motor 64 may be arrangedto rotate stub shaft 62, piston 30, stub shaft 34, and movable platemember 14. Thus, when fluid pressure is applied to the face 46 of piston30 and piston 30 has been displaced rightward so as to displace movableplate member 14 rightward with respect to stationary plate member 12,energization of stepping motor 64 will be operative to rotatablydisplace movable plate member 14 with respect to stationary plate member12. By arranging the spacing of the steps of the step motor 64 in any ofthe well known ways, the single passage means 54 of the movable platemember 14 may be aligned with selected ones of the passages 22 so as topermit, upon leftward displacement of the piston 30, directcommunication between the spray apparatus supply hose 56 and theselected one of the material supply hoses 24, 26.

With reference now to FIGS. 1 and 2 it can be seen that passage means 54of the movable plate member 14 and the passages 22 of the stationaryplate member 12 are arranged to be equidistantly spaced from the axis16. Furthermore, passages 22 may be arranged to be angularlyequidistantly spaced about the periphery of stationary plate member 12.As illustrated in FIG. 2, there are six passages 22 arranged about thestationary plate member 12. It will be appreciated that the number ofpassages 22 is dependent only on the size of the passages 22 and thesize of stationary plate member 12. It can also be seen that thestationary and movable plate members 12, 14 preferably are of circularconfiguration. It will be appreciated that, while reference is madeherein to the passages 22 as being individual passages and passage 54has been referred to as a single passage, passage 54 could be aplurality of passages in any desired configuration, each of which couldbe communicated to one of a plurality of spray apparatus supply hoses.The passages 22 of stationary member 12 could be similarly arranged andconfigured and could communicate with a plurality of hoses 24, 26 eachof which would then communicate with a reservoir of sprayable material.The advantage of this arrangement would be to permit the supply of asingle sprayable material to a plurality of spray nozzles as may be usedfor example to apply coatings to a large surface area when a singlespray apparatus would not have sufficient delivery capability.

Referring now to FIG. 3, the changer apparatus according to the presentinvention is illustrated as applied to a powder paint spray apparatusoperation utilizing an electrostatically charged powder spray apparatus66. Powder spray apparatus 66 is electrostatically charged fromelectrostatic charging means 68 through conductors 70. Electrostaticcharging apparatus 68 is illustrated as being energized from aconventional AC electrical source through electric line cord 72.Electrostatic powder spray apparatus 66 is operative to provide a sprayof electrostatically charged powder coating material to the surface of amember to be coated, shown as 74. As is well known, the powder paintmaterial will be uniformly distributed and will adhere to member 74through the action of the electrostatic charge. In the spray coating ofautomobile bodies, for example, as discussed hereinabove it isfrequently necessary that successive spray applications of material tosuccessive body panels be of differing colors. In order to facilitate arapid and contamination-free change of the powder being provided to thepowder spray apparatus, the changer of the present invention is arrangedto communicate with a plurality of reservoirs of fluidized powdercoating material through a plurality of connecting hoses 24. Forexample, FIG. 3 illustrates a pair of connecting hoses 24 beingcommunicated to reservoirs 76, 78 each of which contains a fluidized bedof powder material of differing colors and a venturi-type powder pump80, 82. A pneumatic fluid line extends from the control system 84 toeach of the powder pumps 80, 82 for providing an energizing fluid flowfor the selected material. In addition, hose 26 may be communicated to asource of flushing agent. One convenient flushing agent is shop airwhich may be used to purge the hoses and passages downstream from thechanger apparatus between successive applications of powder coatingmaterial.

In operation, the present invention functions as follows. A flushingagent such as shop air is communicated through hose 26 and through theappropriate passages of the changer apparatus 10 to the spray apparatussupply hose 56 and the spray apparatus 66. After a sufficient period oftime has elapsed to assure that all residue powders have been exhaustedfrom the spray apparatus supply passage 56 and from the spray apparatus66, the control system 84 will command the application of fluidpressure, which may also be shop air, to fluid conduit 36 and the face46 of piston 30 to cause movable plate member 14 to translate rightward,relative to FIGS. 1 and 3, away from the stationary plate member 12.Proximity sensor switch 86 will respond to plate 14 reaching the extremerightward position so that stepping motor 64 may be actuated torotatably displace movable plate member 14. Step motor 64 may bearranged to rotate clockwise and/or counterclockwise a predeterminedangular distance to align passage 54 with a selected one of the passages22 so that upon application of fluid pressure to passage 38 and face 48of piston 30 and leftward displacement of rotatably plate member 14, thespray apparatus supply hose 56 will be placed in fluid communicationwith the selected one of the powder hoses 24 and its associated materialreservoir so that the application of the appropriate powder coatingmaterial to the next successive body panel 74 may be achieved. Uponleftward displacement of movable plate member 14, proximity sensorswitch 86 will inform the control system 84 that leftward displacementhas been achieved and the material reservoir powder pump for theselected material may be energized. Due to the dual sealing action ofthe inter-plate sealing means 50, 60 powder supplied from the oneselected powder reservoir 76, 78 which communicates directly with thespray apparatus supply hose 56 will be prevented from entering andaccumulating in the passages 22 which communicate with the nonselectedreservoirs. After the passage of an amount of time selected tocorrespond with the rate of travel of the body panel 74 on the conveyorapparatus past the nozzle 88 of spray apparatus 66, the control system84 will depressurize the powder pump in the reservoir of the selectedmaterial and the movable plate member 14 will be automatically indexedto place the spray apparatus supply hose 56 in communication with theflushing agent supply hose 26 so that residue powders may be exhaustedfrom supply hose 56 and from the spray apparatus 66. In the preferredembodiment, the flushing agent may be pressurized shop air butalternatively, the spray apparatus 66 and supply hose 56 may be flushedby a vacuum operation in which the powders which act as residue withinthe spray apparatus and the spray apparatus supply hose may be collectedand returned to the respective fluid supply reservoirs 76, 78.

Referring now to FIG. 4, a representative control system 84 forcontrolling the sequence of operation of the changer apparatus accordingto the present invention is illustrated. In the illustrated controlsystem, the principal element of the control is the memory andelectrical sequence signaller 90 which may be, for example, an EdonMemo-Chain control mechanism having memory capability. This centralprocessing unit 90 receives material selection indications from thepowder selectro 92 and applies suitable control signals to the pneumaticcontrol means 94. Unit 90 also applies suitable electrical signals toindexer 64 to accomplish clockwise or counterclockwise stepping motionwhen switching from one of the selected passages 22 of stationary platemember 12, to the flushing position, and to a second selected passage 22of the stationary plate member 12. Pneumatic control means 94 receivespneumatic fluid, which may also be shop air, under pressure frompneumatic source 96. Pneumatic control means 94 may be comprised, forexample, of suitable electromechanical valve means for controlling theapplication of pneumatic pressure to a selected pumping means 80, 82,for example and to control actuation of the cylinder means 28. Materialto be sprayed would therefore be pumped by pump means 80, 82 through theassociated material supply hose 24 to changer 10. This material would bedelivered to spray apparatus supply hose 56 to be sprayed from nozzle88. The lateral position of movable plate member 14 relative tostationary plate member may be communicated from switch member 86 tocentral processing unit 90 by conductor means 98.

Referring now to FIG. 5, a fragmentary view of a portion of thestationary and rotary plate members 12, 14 according to the presentinvention and showing an alternate valving and sealing mechanism isillustrated. According to the structure of FIG. 5, each of the passages22 of the stationary plate member 12 is provided with a displaceablecheck valve means 100 and a separate sealing means 102. In theillustrated embodiment, the check valve means is comprised of a ballmember 104 which is urged toward a seat 106 by resilient means 108.Valve seat 106 is provided in combined valve seat and seal member 110which may be formed of a resilient material. Movable plate member 14 issimilarly provided with a complementary seal forming member 1 12 whichis arranged to coact with the member 110 to provide a fluid tight sealbetween the passage 122 of stationary member 12 and the passage means 54of the rotary member 14. As illustrated in the FIG. 5 embodi- 8 ment,cooperating sealing member 12 is provided with a central aperture 158which is aligned with the similarly provided aperture within the sealmember 110.

Passage 54 is further provided with means defining a check valvedisplacing element, finger 114, which is situated within passage means54 and arranged to project outwardly from the movable member 14 so as toengage, and displace, the ball member 104 of the check valve means 100.In the illustrated embodiment, each of the passages 122 of thestationary member 12 is provided with a combined valve seat and sealmember 110. The cooperating seal member 112 is here illustrated as beingan annular member arranged about the periphery of movable plate member14 and which is radially spaced so as to engage the cooperating seatforming member 110. As illustrated, seal member 112 possesses but asingle aperture 158.

It will be appreciated that the present invention readily accomplishesits stated objectives. By providing structure which is situated betweenthe confronting faces of the stationary and rotary plate members, doublesealing is provided to 1) provide a fluid tight seal between the sprayapparatus supply hose 56 and the selected supply passage of thestationary plate member in communication with hose 56 while 2) sealingthe nonselected supply passages of the stationary plate member from anycontamination which might be inadvertently introduced into the regionbetween the plate members 12, 14 from the operation of changer 10.Furthermore, the. present invention provides a mechanism by which anyresidual powders remaining within the spray apparatus supply structuremay be exhausted so as to avoid any contamination forming residues whenswitching from a spray operation involving a first sprayable material toa spray operation involving a second sprayable material which may beincompatible with the first sprayable material because of color or otherdifferences. By the rather direct expedient of enlarging the diameter ofthe stationary and rotary plate members and by suitably arranging theindexing means 64 to accommodate for different sizes and differentangular spacings between the stationary plate member passages, anindefinitely large number of different sprayable materials may becommunicated to a single spray apparatus while avoiding the risk ofcontamination between different sprayable materials and assuring theavailability of a flushing action when switching between two dissimilarand incompatible sprayable materials. Furthermore, multiple sprayapparatus may be provided by utilizing multiple porting and multiplesupply hoses.

While my invention has been described with reference to a particularutilization and specific exemplary structure has been described, thepractitioner will recognized that certain modifications may readily bemade. For example, the changer apparatus may be used with materialsupplies which are not fluidized and need not be limited to use withpowders. The translatory and indexing structure may be constructed toprovide a nonrotary piston member sealingly coupled to a single throughshaft with the shaft being slidingly splined to either the movable plateor the indexer, or the shaft may be fixedly attached to both with theindexer being slidingly and nonrotarily coupled to the stationary platemember.

I claim:

1. Apparatus for communicating a powder spray gun with a plurality offluidized powder sources while avoiding cross contamination of powderscomprising in combination:

a stationary plate member having a powder side and a sealing side, aplurality of powder passages and at least one flushing passage, saidpassages extending through said plate from the powder side to thesealing side;

hose means coupled to said powder passages on the powder side of saidplate for fluid-tight communication of said powder passages with theplurality of powder sources; further hose means coupled to said at leastone flushing passage on the powder side of said plate;

means coupled to said further hose means for flowing a flushing mediumtherethrough;

plate valve means supported in closely spaced relation to saidstationary plate member and having a flow passage means extendingthrough said plate valve means and aligned for fluid communcation withsaid powder passage and said at least one flushing passage;

hose means coupled to said flow passage means for communicating saidflow passage means with the spray gun;

means connected to said valve plate means for varying the spatialrelation between said valve plate means and said stationary platemember;

indexing means operative to align said flow passage with a selected oneof said powder and flushing passages;

seal means interposed between said stationary plate member and saidvalve plate means operative to provide sealed communication between saidflow passage and said selected one of said powder and flushing passages;

said plate valve means comprising a plate member mounted for rotationabout an axis, said rotation axis being arranged to extend through thestationary plate member, and said spatial relation varying meanscomprise cylinder means interconnecting said stationary plate member andsaid plate valve means actuable to increase the spatial relation to afirst predetermined amount and to decrease the spatial relation to asecond predetermined amount; and

said indexing means comprising step motor means operative when thespatial relation between the stationary plate member and the valve platemeans is at the first predetermined amount to rotate said valve platemeans about said axis until said flow passages is aligned with theselected one of the powder and flushing passages and to actuate saidpiston means to establish a spatial relation of the second predeterminedamount.

2. The apparatus of claim 1 including control means to automatically andsequentially operate the piston means and the indexing means tocommunicate different selected ones of the powder passages with the flowpassage and to communicate the flow passage with the flushing passagebetween successive different powder passage communications.

3. ApparatusYor communicating a powder spray gun with a plurality offluidized powder cources while avoiding cross contamination of powderscomprising in combination:

10 a stationary plate member having a powder side and a sealing side, aplurality of powder passages and at least one flushing passage, saidpassages extending through said plate from the powder side to thesealing side; hose means coupled to said powder passages on the powderside of said plate for fluid-tight communication of said powder passageswith the plurality of powder sources; further hose means coupled to saidat least one flushing passage on the powder side of said plate;

means coupled to said further hose means for flowing a flushing mediumtherethrough;

plate valve means supported in closely spaced relation to saidstationary plate member and having a flow passage means extendingthrough said plate valve means and aligned for fluid communication withsaid powder passages and said at least one flushing passage;

hose means coupled to said flow passage means for communicating saidflow passage means with the spray gun;

means connected to said valve plate means for varying the spatialrelation between said valve plate means and said stationary platemember;

indexing means operative to align said flow passage with a selected oneof said powder and flushing passages;

seal means interposed between said stationary plate member and saidvalve plate means operative to provide sealed communication between saidflow passage and said selected one of said powder and flushing passages;and

seal means interposed between said stationary plate member and saidplate valve means operative to seal closed the nonselected ones of thepowder and flushing passages;

said seal means comprising a. a plurality of first seal element meanssituated on said stationary plate member in proximity to the sealingside thereof and arranged to be in surrounding relation to the sealingside orifice of each of the powder and flushing passages and b. meansdefining second seal element means positioned on said plate valve memberin juxtaposed relation to the plurality of first seal element means, thesecond seal element means including a passage means aligned with theflow passage means of the plate valve means to provide unrestrictedmaterial flow through from a selected one of the powder and flushingpassages to said flow passage means.

4. The apparatus of claim 3 including further a plurality of check valvemeans situated in the powder passages and having orifices extending fromthe seal side of the stationary plate member toward the valve platemeans, and valve operating means extending from the flow passage,operative to engage and open the check valve means situated in theselected one of the powder and flushing passages.

5. The apparatus of claim 4 wherein each of said check valve meanscomprise displaceable ball valve member, means resiliently biasing saidball valve member toward a valve seat and said valve operating meanscomprise a projecting finger element situated in the flow passage meansof said plate valve means.

1. Apparatus for communicating a powder spray gun with a plurality offluidized powder sources while avoiding cross contamination of powderscomprising in combination: a stationary plate member having a powderside and a sealing side, a plurality of powder passages and at least oneflushing passage, said passages extending through said plate from thepowder side to the sealing side; hose means coupled to said powderpassages on the powder side of said plate for fluid-tight communicationof said powder passages with the plurality of powder sources; furtherhose means coupled to said at least one flushing passage on the powderside of said plate; means coupled to said further hose means for flowinga flushing medium therethrough; plate valve means supported in closelyspaced relation to said stationary plate member and having a flowpassage means extending through said plate valve means and aligned forfluid communcation with said powder passage and said at least oneflushing passage; hose means coupled to said flow passage means forcommunicating said flow passage means with the spray gun; meansconnected to said valve plate means for varying the spatial relationbetween said valve plate means and said stationary plate member;indexing means operative to align said flow passage with a selected oneof said powder and flushing passages; seal means interposed between saidstationary plate member and said valve plate means operative to providesealed communication between said flow passage and said selected one ofsaid powder and flushing passages; said plate valve means comprising aplate member mounted for rotation about an axis, said rotation axisbeing arranged to extend through the stationary plate member, and saidspatial relation varying means comprise cylinder means interconnectingsaid stationary plate member and said plate valve means actuable toincrease the spatial relation to a first predetermined amount and todecrease the spatial relation to a second predetermined amount; and saidindexing means comprising step motor means operative when the spatialrelation between the stationary plate member and the valve plate meansis at the first predetermined amount to rotate said valve plate meansabout said axis until said flow passages is aligned with the selectedone of the powder and flushing passages and to actuate said piston meansto establish a spatial relation of the second predetermined amount. 2.The apparatus of claim 1 including control means to automatically andsequentially operate the piston means and the indexing means tocommunicate different selected ones of the powder passages with the flowpassage and to communicate the flow passage with the flushing passagebetween successive different powder passage communications.
 3. Apparatusfor communicating a powder spray gun with a pluralIty of fluidizedpowder cources while avoiding cross contamination of powders comprisingin combination: a stationary plate member having a powder side and asealing side, a plurality of powder passages and at least one flushingpassage, said passages extending through said plate from the powder sideto the sealing side; hose means coupled to said powder passages on thepowder side of said plate for fluid-tight communication of said powderpassages with the plurality of powder sources; further hose meanscoupled to said at least one flushing passage on the powder side of saidplate; means coupled to said further hose means for flowing a flushingmedium therethrough; plate valve means supported in closely spacedrelation to said stationary plate member and having a flow passage meansextending through said plate valve means and aligned for fluidcommunication with said powder passages and said at least one flushingpassage; hose means coupled to said flow passage means for communicatingsaid flow passage means with the spray gun; means connected to saidvalve plate means for varying the spatial relation between said valveplate means and said stationary plate member; indexing means operativeto align said flow passage with a selected one of said powder andflushing passages; seal means interposed between said stationary platemember and said valve plate means operative to provide sealedcommunication between said flow passage and said selected one of saidpowder and flushing passages; and seal means interposed between saidstationary plate member and said plate valve means operative to sealclosed the nonselected ones of the powder and flushing passages; saidseal means comprising a. a plurality of first seal element meanssituated on said stationary plate member in proximity to the sealingside thereof and arranged to be in surrounding relation to the sealingside orifice of each of the powder and flushing passages and b. meansdefining second seal element means positioned on said plate valve memberin juxtaposed relation to the plurality of first seal element means, thesecond seal element means including a passage means aligned with theflow passage means of the plate valve means to provide unrestrictedmaterial flow through from a selected one of the powder and flushingpassages to said flow passage means.
 4. The apparatus of claim 3including further a plurality of check valve means situated in thepowder passages and having orifices extending from the seal side of thestationary plate member toward the valve plate means, and valveoperating means extending from the flow passage, operative to engage andopen the check valve means situated in the selected one of the powderand flushing passages.
 5. The apparatus of claim 4 wherein each of saidcheck valve means comprise displaceable ball valve member, meansresiliently biasing said ball valve member toward a valve seat and saidvalve operating means comprise a projecting finger element situated inthe flow passage means of said plate valve means.